首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4660篇
  免费   354篇
  国内免费   20篇
耳鼻咽喉   20篇
儿科学   167篇
妇产科学   136篇
基础医学   731篇
口腔科学   40篇
临床医学   607篇
内科学   956篇
皮肤病学   101篇
神经病学   495篇
特种医学   82篇
外科学   415篇
综合类   18篇
一般理论   3篇
预防医学   525篇
眼科学   113篇
药学   277篇
  1篇
中国医学   2篇
肿瘤学   345篇
  2023年   62篇
  2022年   102篇
  2021年   222篇
  2020年   118篇
  2019年   160篇
  2018年   199篇
  2017年   151篇
  2016年   130篇
  2015年   192篇
  2014年   251篇
  2013年   293篇
  2012年   354篇
  2011年   388篇
  2010年   210篇
  2009年   152篇
  2008年   295篇
  2007年   274篇
  2006年   275篇
  2005年   234篇
  2004年   224篇
  2003年   181篇
  2002年   146篇
  2001年   30篇
  2000年   12篇
  1999年   21篇
  1998年   32篇
  1997年   25篇
  1996年   26篇
  1995年   21篇
  1994年   28篇
  1993年   21篇
  1992年   13篇
  1991年   11篇
  1990年   10篇
  1989年   12篇
  1988年   10篇
  1987年   7篇
  1986年   6篇
  1985年   11篇
  1984年   7篇
  1983年   9篇
  1982年   8篇
  1980年   10篇
  1975年   6篇
  1974年   12篇
  1973年   6篇
  1971年   7篇
  1970年   4篇
  1968年   4篇
  1964年   4篇
排序方式: 共有5034条查询结果,搜索用时 31 毫秒
91.
Objective: To evaluate the impact of amniotic fluid “sludge” (AFS) on the risk of preterm delivery and to describe the effect of antibiotic treatment in that situation.

Methods: Case–control study including singleton pregnancies with or without AFS, between 15–32 weeks of gestation. Factors associated with preterm delivery before 32 weeks, 34 weeks and 37 weeks were evaluated with univariate and multivariate logistic regression. Since all women with AFS in this study were treated with antibiotics, a historical comparison was performed with similar patients with AFS found before 2007 and not treated with antibiotics.

Results: AFS was observed in 90/1220 patients (7.4%). AFS was associated with shorter cervical length, greater body mass index, cervical cerclage and preterm birth before 28 weeks. However, after adjustment, AFS did not remain associated with preterm delivery before 32 or 34 weeks. The historical comparison suggested that azithromycin could significantly reduce the risk of preterm delivery before 34 weeks (odds ratio: 0.2; 95% CI: 0.04–0.92).

Conclusions: AFS, treated with azithromycin, was associated with a higher risk of prematurity, but not independently after adjustment for cervical length and second trimester vaginal bleeding. Further studies need to evaluate the effect of antibiotics in pregnancies with AFS.  相似文献   

92.
93.
Paraganglioma in pregnancy is an exceedingly rare and potentially life‐threatening diagnosis. It is important that the clinicians consider secondary causes when women present with hypertension in early pregnancy.  相似文献   
94.
After 30 years of hematopoietic stem cell use for various indications, umbilical cord blood is considered as an established source of cells with marrow and postmobilization peripheral blood. The limited number of cells still remains a problematic element restricting their use, especially in adults who require to be grafted with a higher cell number. Improving the quality of harvested cord blood, at least in terms of volume and amount of cells, is essential to decrease the number of discarded units. In this review, we examine several variables related to parturient, pregnancy, labor, delivery, collection, the newborn, umbilical cord, and placenta. We aim to understand the biologic mechanisms that can impact cord blood quality. This knowledge will ultimately allow targeting donors, which could provide a rich graft and improve the efficiency of the collection.  相似文献   
95.

Objective

To examine the feasibility and preliminary effectiveness of an individualized yoga program.

Design

Pilot randomized controlled trial.

Setting

Military medical center.

Participants

Patients (N=68) with chronic low back pain.

Interventions

Restorative Exercise and Strength Training for Operational Resilience and Excellence (RESTORE) program (9–12 individual yoga sessions) or treatment as usual (control) for an 8-week period.

Main Outcome Measures

The primary outcome was past 24-hour pain (Defense & Veterans Pain Rating Scale 2.0). Secondary outcomes included disability (Roland-Morris Disability Questionnaire) and physical functioning and symptom burden (Patient-Reported Outcomes Measurement Information System-29 subscales). Assessment occurred at baseline, week 4, week 8, 3-month follow-up, and 6-month follow-up. Exploratory outcomes included the proportion of participants in each group reporting clinically meaningful changes at 3- and 6-month follow-ups.

Results

Generalized linear mixed models with sequential Bonferroni-adjusted pairwise significance tests and chi-square analyses examined longitudinal outcomes. Secondary outcome significance tests were Bonferroni adjusted for multiple outcomes. The RESTORE group reported improved pain compared with the control group. Secondary outcomes did not retain significance after Bonferroni adjustments for multiple outcomes, although a higher proportion of RESTORE participants reported clinically meaningfully changes in all outcomes at 3-month follow-up and in symptom burden at 6-month follow-up.

Conclusions

RESTORE may be a viable nonpharmacological treatment for low back pain with minimal side effects, and research efforts are needed to compare the effectiveness of RESTORE delivery formats (eg, group vs individual) with that of other treatment modalities.  相似文献   
96.

Objective

To assess the feasibility of measuring ventilatory threshold (VT) in higher-level motor-complete spinal cord injury (SCI) using 4 different analysis methods based on noninvasive gas exchange.

Design

Observational.

Setting

Laboratory testing.

Participants

Individuals with C4-T6 motor-complete SCI (16 paraplegia, 22 tetraplegia; American Spinal Injury Association Impairment Scale A/B; 42±10 years old).

Interventions

Not applicable.

Main Outcome

VT from a graded arm cycling test to volitional exhaustion using 4 methods: ventilatory equivalents, excess CO2, V-slope, and combined method.

Results

VT could be identified in all individuals with paraplegia, but in only 68% of individuals with tetraplegia. Individuals without observable VT completed the graded exercise test with lower ventilatory rate, peak power output, and peak oxygen consumption (Vo2peak) (all P<.05), compared to those with a detectable VT. Bland-Altman plots indicate minimal bias between methods (range: 0.01-0.03 L/min), with 95% limits of agreement of the difference within 0.25 L/min. Absolute V.o2 at VT with individual methods were all correlated to peak power output (r>0.74; P<.01) and Vo2peak (r>0.91; P<.01), with negligible differences between methods.

Conclusions

The assessment of VT is a feasible alternative to peak exercise testing for aerobic fitness in individuals with higher-level, motor-complete SCI, although care should be taken when interpreting VT in individuals with tetraplegia who have lower cardiorespiratory fitness and lower peak power outputs.  相似文献   
97.

Purpose

The relation between driving pressure (plateau pressure-positive end-expiratory pressure) and mortality has never been studied in obese ARDS patients. The main objective of this study was to evaluate the relationship between 90-day mortality and driving pressure in an ARDS population ventilated in the intensive care unit (ICU) according to obesity status.

Methods

We conducted a retrospective single-center study of prospectively collected data of all ARDS patients admitted consecutively to a mixed medical-surgical adult ICU from January 2009 to May 2017. Plateau pressure, compliance of the respiratory system (Crs) and driving pressure of the respiratory system within 24 h of ARDS diagnosis were compared between survivors and non-survivors at day 90 and between obese (body mass index?≥?30 kg/m2) and non-obese patients. Cox proportional hazard modeling was used for mortality at day 90.

Results

Three hundred sixty-two ARDS patients were included, 262 (72%) non-obese and 100 (28%) obese patients. Mortality rate at day 90 was respectively 47% (95% CI, 40–53) in the non-obese and 46% (95% CI, 36–56) in the obese patients. Driving pressure at day 1 in the non-obese patients was significantly lower in survivors at day 90 (11.9?±?4.2 cmH2O) than in non-survivors (15.2?±?5.2 cmH2O, p?<?0.001). Contrarily, in obese patients, driving pressure at day 1 was not significantly different between survivors (13.7?±?4.5 cmH2O) and non-survivors (13.2?±?5.1 cmH2O, p?=?0.41) at day 90. After three multivariate Cox analyses, plateau pressure [HR?=?1.04 (95% CI 1.01–1.07) for each point of increase], Crs [HR?=?0.97 (95% CI 0.96–0.99) for each point of increase] and driving pressure [HR?=?1.07 (95% CI 1.04–1.10) for each point of increase], respectively, were independently associated with 90-day mortality in non-obese patients, but not in obese patients.

Conclusions

Contrary to non-obese ARDS patients, driving pressure was not associated with mortality in obese ARDS patients.
  相似文献   
98.
99.
100.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号